Revert of [crankshaft] Fixing ES6 tail call elimination.

src/crankshaft/lithium.cc

Index: src/crankshaft/lithium.cc
diff --git a/src/crankshaft/lithium.cc b/src/crankshaft/lithium.cc
index a1a73e4beb84042075fdf72be63a93ea8b170a06..20c4e431253c65019e275c6d94e8d3d42157da52 100644
--- a/src/crankshaft/lithium.cc
+++ b/src/crankshaft/lithium.cc
@@ -508,14 +508,6 @@
   status_ = ABORTED;
 }
 
-LInstruction* LChunkBuilderBase::AssignEnvironment(LInstruction* instr,
-                                                   HEnvironment* hydrogen_env) {
-  int argument_index_accumulator = 0;
-  ZoneList<HValue*> objects_to_materialize(0, zone());
-  instr->set_environment(CreateEnvironment(
-      hydrogen_env, &argument_index_accumulator, &objects_to_materialize));
-  return instr;
-}
 
 LEnvironment* LChunkBuilderBase::CreateEnvironment(
     HEnvironment* hydrogen_env, int* argument_index_accumulator,